Power divider



Aug. 4, 1953 D. E. ROWE POWER DIVIDER Filed Sept. 18, 1945 ANTENNA ANTENNA RECEIVER INVENTOR DELMAN E. ROWE M WK ATTORNEY Patented Aug. 4, 1953 me'sne assignments, to' the Unit rst t Ameliea fi'as afmeptesented ;-by the 7 Secretary .of

MY-presentrinventiomrelates' in"general to' ap- "paratus for controlling. the "intensity --or guided electromagnetic energy and imore particularly to the provisional a combined voltagedivider, variable attenuatorrand switch in a'transmission line system.

This invention isan improvement upon the invention "disclosed in my "copending application Serial N0. 6l3,511,"fi18d August30, 1945.

In my present" invention 'I"provide a' simple mechanism for varying the intensity of the signal in a coaxialline'and for switching that signal be switched on and'oif or the signal therein 'may be attenuated.

Itisac'cordingly an object'of my invention to providein a singleapparatus a variable attenuator, switch and power divider fordividing the powerin acoaxial line system and'*for-' switching on and off the power in one branch of the apparatus.

It is a further object ofmy invention to provide suclra combined variable" attenuator, switch and power divider that will be light in weight, simple tomanufacture and simple to adjust and operate.

It is astillfurther object of -my invention" to providesu'ch an attenuatonqswitch and power divider that will control positively the switching on and ofi of the power in one branch thereof.

Other objects and features of my present invention will become apparent upon a careful consideration of the following detailed description when taken together with the accompanying drawing the figure of which illustrates a typical embodiment of the invention.

In the drawing, a first coaxial line I having an outer conductor 2 and an inner conductor 3 has joined thereto in a T-J'unction a second coaxial line 4 having an outer conductor 5, an inner conductor 6 and an end closure 8 for the far end thereof. The inner conductor 3 of the first coaxial line I has a hole 1 cut transversely therein opposite to the open portion of the second coaxial line 4. The inner conductor 6 of the second coaxial line 4 is slidably mounted therein, being held slidably by a portion of the end closure 8. The end closure 8 is inwardly elongated along the axis of the second coaxial line 4 and progressively reduced in diameter. The end of the -inner -==conductor '-6 directed toward thefir-st ccaxial' line 1 has spring fingered contactors 9 therein. These -'cc ntactors 9 make contact with the hole T in the inner conductor-e'of the first coaxial line I when the slidable-inner conductor 6 of the second coa-xial line-tispushed toward and'into the :hole 1. The inner diameter -D of the outer con- -ductor 5 of the secondcoaxial 'line- 4-is substan- -tially smaller than the inner diameter of the fiI-"st coaxial-dine. This is made smaller so that when the slidable inner conductor 6 is retracted from the hole 1, thesection of the line l that 'hasno inner conductor 'thereinwill 'forma section or hollow wave guide operated beyond cut off'frequency. "The inner diameter D is progres- --sively increased in' -sloped steps D --and D"- toward the closed-end ofthe-second coaxial line "4. correspondingly, the end closure' 8 is *as i aforementioned progressively reduced in its cross sectional diameter along its inwardly elongated portion to match the increases in internal diameter of -the'outer conductor 5. '-A third coaxial line 10,-ha'ving an outer conductor ll and ani inner conductor- |2,--isjoined in T-junction "fashion to --the second coaxialline-- 4' near the closed end--thereof. -The closed-end of the second coaxial line- 4 may thenbecome a short circuited coaxial line stub' having adepth substantially equ'al to one-qua'rterthe length of a wave ofenergy therein at the operative frequency form effectively an impedance matching stub "and support for-the inner conductor 6. This stub preferablyhas-a low "Q.

In explaining the operation of "the apparatus of -my-inventionfit will be convenient to assume that the device is in use in a transmission line system connecting two radio antennas l3 and M in parallel to a radio receiver I 5. Accordingly, one end of the first coaxial line I, the lower end on the drawing, is connected to a radio receiver l5, and the upper end of the coaxial line I is connected to a first radio antenna l3 and the free end of the third coaxial line I0 is connected to a second radio antenna I4. If now, the slidable inner conductor 6 of the second coaxial line 4 is pushed into the hole 1 and engaged into contact with the inner conductor 3 of the first coaxial line I, signals from both antennas will be fed simultaneously into the receiver l5. Now if the slidable inner conductor 6 be retracted from the hole 1, the second antenna I4, namely the one connected to the third coaxial line [0, will no longer be efiectively connected to the receiver, and signals from only one antenna I3,

erated beyond cut off, The small size of the div ameter D near the first line I is desirable to prevent large changes in the impedance of the first line I when the slidable inner conductor 6 is inserted in the hole 1 or withdrawn therefrom. This is so because the hole 1 may be made relatively small when the diameter D is small The apparatus of my invention"may'also be"' used in a system in which electric power is) being fed to two different users of that power. Thus, if a generator of power beconnected to the lower end of the first coaxial line I, and a first user of this power be connected to the upper end of the same coaxial line I, and a second user of this power be connected to the free end of the third coaxial line l0, power will be fed in parallel to both users when the slidable inner conductor 6 is engaged electrically in the hole 1 in the inner conductor 3. When this slidable inner conductor 6 is retracted from the hole 1, power will no longer be fed to the second user connected to the third coaxial line 10, but will be fed solely to the first user.

The increasing inner diameter D, D, and D" of the outer conductor 5 and that of the projection of the end closure 8 of the second coaxial line 4 provides broad-banding characteristics in this coaxial line. The impedance matching stub end of the second coaxial line 4 aids in matching impedances to power being interchanged between the second coaxial line 4 and the third coaxial line 10. This stub is proportioned to have a low Q, in order further to enhance the broadband characteristics. Obviously, if the inner conductor 6 be placed near but not firmly in contact with the opening I in the inner conductor 3, there will be attenuation of signals passing between these two conductors but not complete elimination, since electrical lines of force will pass from the slidable conductor 6 I to the inner conductor 3 of the first coaxial line I. It is only when the slidable inner conductor 6 is retracted a suflicient distance from the hole 1 in the inner conductor 3 to break all electrostatic lines of force between these two inner conductors that a switching action takes place and that the portion of the second coaxial line 4 left without an inner conductor operates as a wave guide beyond cut off.

Although I have shown and described only a certain specific embodiment of my invention, I am fully aware of the many modifications possible thereof. Therefore this invention is not to be limited except insofar as is necessitated by the prior art and the spirit of the appended claims.

I I claim:

1. A combined power divider, attenuator and switch for use in transmission lines comprising, a first coaxial line having first inner and outer conductors and two open ends, a second coaxial line of relatively smaller inner diameter than said first line having second inner and outer conductors,'and oneopen and one closed end, means for connecting said open end of said second line to said first line through a side thereof between said two open ends, said second inner conductor being axially slidably mounted in said second line and adapted to make slidable electrical contact with said first inner conductor, said first inner conductor having a substantially transverse hole therein to receive the thereunto directed end of said second conductor in said slidable electrical contact, said second line becoming a wave guide operated beyond its out ofi frequency at normal operative frequencies when said second inner conductor is retracted from said first inner conductor, a third coaxial line having third inner and outer conductors and two open ends, and means for connecting one end of said third line to said second line through a side thereof near said closed end.

2. The apparatus of claim 1 in which the inner diameter of said second coaxial line is progressively increased in steps toward said closed.end and the portion of said closed end beyond the junction between said second and third lines is a short circuited stub of relatively low Q having a length substantially equal to one quarter of a wave length therein of energy at the operative frequency.

DELMAN E. ROWE.

References Cited in the file of this patent UNITED STATES PATENTS 

